Method for producing very thin and bright metal wires and profiles



June 5, 1965 H. LASKE METHOD EOE PEoDUcING VERY THIN AND BRIGHT METAL wIREs AND PROFILES Filed June 2. 1961 HANS LAS/f Arron/vnl MCT CGH s" m n) 77N@ F/G. 5

United States Patent O 3,188,735 METHD FR PRDUCING VERY THilN AND BRIGHT METAL WIRES AND PROFKLES Hans yLastre, nuruper Chaussee '73, Hamburg- Bahrenfeld, Germany y Filed fune 2, 196i, Ser. No. 114,555 Claims priority, application Germany, `fune 27, 1960,

z Claims. (l. zei-sas) The invention relates to an improved method and means f-or producing very thin stretched metal profiles such as thin wires, strips, bands, and the like, by drawing or rolling those profiles when coated with some material facilitating the drawing or rolling process, which material is removed after the reducing procedure. Here-tofore, in the employment of the coating metal was removed by means of acids or alkalines.

The present 'application is a continuation-impart of my copending U.S. application Serial No. 30,863, led on May 23, 1960, now abandoned. In that application there was disclosed, by way of example, a method for producing very thin and bright metal wires, especially wires having a diameter of less than 0.00005 inches. The method `and means `for carrying it out are equally well applicable to all very thin-stretched metal profiles, as above mention-ed, and not only to wires,

Such -wires could heretofore be produced, e.g. by means of the Wollaston method. In this method the wires to be drawn are rst coated, e.g. by electro-plating with a metal coat.' After the wires have passed one or more dies the coat which facilitates the drawing is removed by means of acids or alka-lies, which makes bright wires.

One object of the invention is a new method for producing very thin and bright metal profiles, such as wires in which the latter lare not at all contacted with any corrosive medium such as acid, lye, Ioxygen or other chemical substances and in which any subsequent neutralizing steps are lobviated.

Another object of the invention is to produce bright metal wires having diameters less than attainable with the presently known methods.

According to the present invention the metal prolile to be treated consisting e.g. of iron or nickel is coated with 4a metal or non-metallic material the vaporization temperature of which is below the melting point of the material to be processed. The profile is then reduced,

e.g. by drawing or rolling in a manner known per se and afterwards the coating is removed by vaporization of the coating material to leave a bright surface.

It is well known in the practice of drawing or rolling, to use for the coating a met-al e.g. zinc or cadmium The present lmeth-od includes the use of tin and lead as coating materials. In the present invention it is essential that the vaporization temperature of the coa-ting material and r the melting temperature of the material to be processed s'hall be sufficiently different so that the material to be processed will not be affected by the vap-orization step.

lIn order to avoid high vaporization temperatures it is advisable to effect the vap-orization in a vacuum chamber i.e. at lower temperatures.

Another lobject ot the present invention is to pr-ovide the heat for the vaporization of the coating material by conducting an electric current through the material to be processed.

If -ne wire resistors enveloped in closed bulbs have to be produced, the coated wires with connecting electrodes are mounted in the bulb before the vaporization step of the coating material, and then the coating material is vaporized by passing a heating current through the wire.

Furthermore, it is part .of the present invention that the condensation of the vaporized coating material, espe- 3,188,735 Patented June 15, 1965 ICC cially if this is a metallic one, is limited to predetermined areas of the envelope or bulb by differently cooling and heating the latter. The heating may be done by HF- heating coils and the cooling by cooling jackets slipped over the envelope or bulb.

yFurther details and features of the present invention will become apparent from the following description and the attached drawing, which show preferre/i embodiments.

In the drawings:

FIGURE l is a cross-section through a vacuum chamber for vaporizing the coating material and FIGURE 2 is a schematic view of an electric heating system .for tine wires enveloped in a closed bulb.

PIG. 3 is a how sheet of `the claimed process.

As shown diagrammatically in the drawing the thin metal wire is conducted through an electro-plating bath in which the coating material having a vaporization point substantially lower than the melting point of the wire is deposited on the wire. The coated wire is drawn successively thnough ya number of dies until it is reduced to the desired thickness. The wire is next connected across a pair of electrodes, in a container. An inert gas is iritrod-uced into the container and the latter is closed. Current is passed through the coated wire, sufficient to vaporize the deposited coating Without melting the wire proper. The wire freed of the coating is then removed from the container.

As may be seen from the drawings, for the performance of the present invention it is necessary to provide a vacuurn chamber a with a suction pump b, said chamber comprising heating elements c for heat-ing the coated wires d, coils or' the like up to the vaporization point of the coating. material. The coated and, e.g. already, coiled wire d is put into the vacuum chamber 1 for vaporizing the coating material.

According to the size of such vacuum heating chamber it is possible to handle larger or smaller quantities of such wires or even ready-made resistors.

FIGURE 2 shows a `tine wire stretched out in a bulb of glass when vaporizing4 the coating material.

In this figure the resistor wire 11 already drawn and still coated with the material facilitating the drawing procedure is pro-vided with thicker electrodes or mounting wires 12 `and 13 at its both ends.

Preferably before the last drawing step the mounting wires 12 and V13, respectively, are connected to the ends of the resistor wire.

By means of the mounting wires 12 and 13 the resistor Wire 11 has .been fused into the glass bulb and the projection 15 of the glass bulb 14 is cl-osed by Imelting after the filling of the bulb 14 with some protective gas or the like.

To prevent oxidation during the vaporization procedure it is possible to use a special inert gas which after vaporization of the coating may be removed and replaced by such gas as e.g. hydrogen which is required `for the use of the resistor.

The vaporizati-on of the material coating .the wire 11 is performed by closing the switch 16 so as to direct a current from the source 17 through the Wire 11, the current `being controlled by a resistor 1'8 in conjunction with the Vammeter v19.

To prevent .an uncontrolled condensation of the vaporized coating material on the walls of the bulb 14 and, when a metallic coating material is used, to avoid shortcircuiting effects between the two wires 12 and 13 through the condensation deposits, the cross-section of the bulb portion surrounding the wires 12 and 13 is substantially reduced so that coils 20 .and `211 may be slipped over the bulb end-portions and connected `directly to an HF-current generator 22 for creating within .the bulb 14 so high a at such locations will material to certain parts of the wall of the bul-b it is possible to provide at these parts an additional cooling, e.g. the cooling jacket 23 as shown in the drawings.

Instead of heating the wire 11 yby ythe passage of a directY current it is also possible'to induce a How of current by means of a transformer or by causing van eddy current to flow in the conductor 12 by means of external HF-heating means. Y

The envelope or bulb of the resistor need not necessarily Ibe of insulating material but may be of metal from which the connecting wires l2 and 13 are insulated;

Instead ou? a metallic coating material some insulating material with correspondingly low vaporization temperature may be used.

The method according to the invention is not restricted to .wires but maybe adopted for other thin stretched metal proiiles, eg. thin proiiles suc-h as strips and bands as trans- -parent foils for capacitive surface illumination lby electro lluminescence may be produced by the described method. Further, very thin metal strips or small metal plates to be used for electrostatic screening and as a contrast lter inthe production lof cathode ray tubes may also be produced.

What I claim is:

`1. Apparatus for vaporizing a protective coating from very thin and bright meta-l Wires comprising an airtight container Which is provided with a pair of spaced electrodes adapted to be connected to the respective ends of a wire, for vaporizing a protective coating previously applied, .a low frequency electric current supply connected to said electrodes, the portion of the `container enclosing said electrodes being of a reduced cross-section, said apparatus comprising at least one high frequency coil for enclosing said portion, a high frequency generator connected to said coil, said generator being adapted to generate a high temperature in said end portion to thereby prevent condensation of the vaporized coating material on the Walls od said container.Y

2. A method of producing very thin stretched metal proles, suc-h as' thin Wires, strips, bands and the like, to be employed as resistors, comprising coating thc surface of a thin metal proiile having a predetermined melting point with a metallic coating material having a predetermined vaporization point su'bstantlallylovver than the melting point of the metal prolile, `so as to provide a coated thicker metal proilile; reducing the cross-section of the coated proiile by drawing the latter through a number of dies, connecting the respective ends of the proile to a pair of electrodes, fusing Ithe electrodes to a container, introducing an inert gas into the container,

closing the container, removing the coating material from the sunface of the -metal profile by passing electric current therethrough of a strength suhicient to heat the proile beyond the vaporization pointoif the coating material While cooling the container Iduring the step of vaporization to thereby direct the condensation of the vaporized coating material yto predetermined parts `of the container wall and removing the inert gas after the vaporization of the coating.

2f References Cited 'oy the Examiner UNITED STATES PATENTS 669,698 3/01 Ivins. Y 930,723 8/ 09 Von Bolton 29-198 X E0 1,026,383 5/12 Coolidge 29-424 X 1,071,174 8/ 13 Von Pirani etal 205-21 1,082,933 12/ 13 Coolidge 29-420.S X 1,273,506 7/ 18 Lederer 205-21 1,345,441 7/20 Hisamoto 205-21 35 1,597,189 8/-26 Gero 2 9-198 X 1,700,454 1/-29 Schumacher. Y

V1,948,485 2/34 Anselm 294-528 X 2,100,697 11/37 Loewe 2l9-10.41 X 2,447,979 8/48 Hensel et al.

.3 `2,721,372 10/55 `Levi 29-424 X 2,866,262 12/ 58 Mataich 29-424 X 2,913,561 y11/59 Rummel et al 219-l0.43 2,930,879 3/ 60 Scatchard.

4 5 WHITMORE A. WILTZ, Primary Examiner.

HY LAND BIZOT, JOHN F, CAMPBELL, Examzivzers, 

1. APPARATUS FOR VAPORIZING A PROTECTIVE COATING FROM VERY THIN AND BRIGHT METAL WIRES COMPRISING AN AIRTIGHT CONTAINER WHICH IS PROVIDED WITH A PAIR OF SPACED ELECTRODES ADAPTED TO BE CONNECTED TO THE RESPECTIVE ENDS OF A WIRE, FOR VAPORIZING A PROTECTIVE COATIG PREVIOUSLY APPLIED, A LOW FREQUENCY ELECTRIC CURRENT SUPPLY CONNECTED TO SAID ELECTRODES, THE PORTION OF THE CONTAINER ENCLOSING SAID ELECTRODES BEING OF A REDUCED CROSS-SECTION, SAID APPARATUS COMPRISING AT LEAST ONE HIGH FREQUENCY COIL FOR ENCLOSING SAID PORTION, A HIGH FREQUENCY GENERATOR CONNECTED TO SAID COIL, SAID GENERATOR BEING ADAPTED TO GENERATE A HIGH TEMPERATURE IN SAID END PORTION TO THEREBY PREVENT CONDENSATION OF THE VAPORIZED COATING MATERIAL ON THE WALLS OF SAID CONTAINER. 